Abstract

Introduction

Current guidance on the treatment of high blood pressure provides the advice that co-pathology should be taken into account when treatment decisions are made, but does not specify the approach in people with dementia. A relationship between high blood pressure and dementia, all be it complex and variable over time, does exist, making dementia a relevant co-pathology in decisions around the treatment of hypertension. No trial evidence exists however to guide clinical decision making in this specific context and clinicians with theoretical concerns over adverse events or varying priorities may act differently while remaining within the scope of current guidance. To inform the design of potential future research examining the repercussions of different treatment approaches, the way high blood pressure is currently treated in people with dementia and the adverse events they experience need to be understood.

Aims

This thesis reports research which set out to describe the treatment of high blood pressure in people with dementia and the adverse events that this population experienced over a six month period.

Methods

(i) A systematic literature review of observational studies describing the treatment of hypertension in people with dementia was performed.

(ii) A multicentre cohort study, the Hypertension IN Dementia (HIND) study, of 181 participants, recorded information on dependency in activities of daily living (ADLs), cognition, medication, diagnoses, and healthcare use. It provided a detailed description of the treatment of high blood pressure in the study population and the adverse events experienced over a 6 month period.

Results

Literature review: The prevalence of hypertension in people with dementia was 45% (range 36%-84%), of whom 73% (range 48%-85%) were taking at least one antihypertensive. 55% of people with dementia achieved target blood pressure in the one study that reported this. The review found no studies that specifically set out to describe the treatment of high blood pressure in people with dementia in the UK.

Cohort study: 181 participants were recruited from general practices and via memory clinics. The rate of recruitment was low (8%) in the GP arm, resulting in potential selection bias. The study population were mildly cognitively impaired (median MMSE 23 (IQR 18-26)), 56% were dependent for at least one ADL, had a median of 5 (IQR 3-7) diagnoses and were treated with a median of 7 (5-9) medications. High blood pressure was treated in 87% (95% CI 82% - 92%) and target blood pressure was achieved in 57% (95% CI 49% - 64%) of those on treatment, no different from the general population (87% (95% CI 85% - 89%) treated and 52% (95% CI 49% - 55%) achieving target). ACEi/ARBs were the most frequently prescribed antihypertensive class (55%), followed by calcium channel blockers (33%), beta-blockers (30%) and diuretics (21%). Diuretics were less likely to be prescribed than in the general population (21% (95% CI 15%-26%) vs 34% (95% CI 31% - 37%)).

During 6 months follow up the study population reported 475 GP appointments, 65 hospital admissions, 214 falls, 1 myocardial infarction, 6 strokes and 8 deaths. Heart failure, stroke, recurrent falls, falls with fractures, death and GP appointments were more common in the study population than in benchmark populations.

Conclusion

In conclusion in an area where clinicians were acting without a firm evidence base and where there were theoretical concerns around the potential side effects of antihypertensive use, clinicians treated hypertension in people with dementia much as they did in people without dementia.

The same classes of antihypertensives were used to maintain blood pressure at a similar level to that achievable in the general population. Despite a potential selection bias that may have over recruited fitter and milder people with dementia than the overall population, the study population reported a higher level of cardiovascular events, recurrent falls, fractures and adverse symptomatology than those without dementia in benchmark populations. Although this finding could relate to reporting bias or a higher intrinsic cardiovascular risk it raises the possibility that the benefits of antihypertensive treatment are attenuated, while the risks are increased, in people with dementia with implications for the risk-benefit ratio in this population.

Future specific research, using an approach that avoids selection bias, to explore the risk-benefit ratio of antihypertensive treatment in people with dementia is outlined and advice is provided to clinicians managing high blood pressure in people with dementia.